code: def _to_depgraph(self, nodes, head, rel):
      index = len(nodes)
  
      nodes[index].update(
          {
              "address": index,
              "word": self.pred[0],
              "tag": self.pred[1],
              "head": head,
              "rel": rel,
          }
      )
  
      for feature in sorted(self):
          for item in sorted(self[feature]):
              if isinstance(item, FStructure):
                  item._to_depgraph(nodes, index, feature)
              elif isinstance(item, tuple):
                  new_index = len(nodes)
                  nodes[new_index].update(
                      {
                          "address": new_index,
                          "word": item[0],
                          "tag": item[1],
                          "head": index,
                          "rel": feature,
                      }
                  )
              elif isinstance(item, list):
                  for n in item:
                      n._to_depgraph(nodes, index, feature)
              else:
                  raise Exception(
                      "feature %s is not an FStruct, a list, or a tuple"
                      % feature
                  )
  
file_path: nltk/nltk/sem/lfg.py
imports: from itertools import chain
  from nltk.internals import Counter
label_desc: Use image node_id 7 for calling the FStructure obj's underlying member method code with example usage: obj._to_depgraph(nodes, head, rel) without return types